US4979064A - Magnetic recording/playback head comprising a superconducting material - Google Patents

Magnetic recording/playback head comprising a superconducting material Download PDF

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Publication number
US4979064A
US4979064A US07/262,719 US26271988A US4979064A US 4979064 A US4979064 A US 4979064A US 26271988 A US26271988 A US 26271988A US 4979064 A US4979064 A US 4979064A
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US
United States
Prior art keywords
magnetic
gap
recording
superconducting material
head
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
US07/262,719
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English (en)
Inventor
Jean-Claude Mage
Jean-Luc Rolland
Jean-Paul Castera
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Thales SA
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Thomson CSF SA
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Publication date
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Assigned to THOMSON-CSF reassignment THOMSON-CSF ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: CASTERA, JEAN-PAUL, MAGE, JEAN-CLAUDE, ROLLAND, JEAN-LUC
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    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/127—Structure or manufacture of heads, e.g. inductive
    • G11B5/1278—Structure or manufacture of heads, e.g. inductive specially adapted for magnetisations perpendicular to the surface of the record carrier
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/127—Structure or manufacture of heads, e.g. inductive
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/127—Structure or manufacture of heads, e.g. inductive
    • G11B5/17—Construction or disposition of windings
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/127—Structure or manufacture of heads, e.g. inductive
    • G11B5/187—Structure or manufacture of the surface of the head in physical contact with, or immediately adjacent to the recording medium; Pole pieces; Gap features
    • G11B5/23—Gap features
    • G11B5/235—Selection of material for gap filler
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/127—Structure or manufacture of heads, e.g. inductive
    • G11B5/31—Structure or manufacture of heads, e.g. inductive using thin films
    • G11B5/3109—Details
    • G11B5/312—Details for reducing flux leakage between the electrical coil layers and the magnetic cores or poles or between the magnetic cores or poles
    • G11B5/3123—Details for reducing flux leakage between the electrical coil layers and the magnetic cores or poles or between the magnetic cores or poles by using special coil configurations or conductors
    • G11B5/3126—Details for reducing flux leakage between the electrical coil layers and the magnetic cores or poles or between the magnetic cores or poles by using special coil configurations or conductors using superconductors
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/127—Structure or manufacture of heads, e.g. inductive
    • G11B5/31—Structure or manufacture of heads, e.g. inductive using thin films
    • G11B5/3109—Details
    • G11B5/313—Disposition of layers
    • G11B5/3143—Disposition of layers including additional layers for improving the electromagnetic transducing properties of the basic structure, e.g. for flux coupling, guiding or shielding
    • G11B5/3159—Disposition of layers including additional layers for improving the electromagnetic transducing properties of the basic structure, e.g. for flux coupling, guiding or shielding superconductive layers
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/10—Structure or manufacture of housings or shields for heads
    • G11B5/11—Shielding of head against electric or magnetic fields

Definitions

  • the present invention concerns a magnetic recording/playback head comprising a superconducting material and, in particular, a magnetic head in which a superconducting material is used to channel the magnetic flux emitted by the head towards the magnetic recording support.
  • Magnetic recording/playback heads consist of a magnetic circuit 1 of high permeability, comprising a non-magnetic gap 2, of a thickness e, and an electrical circuit 3 which surrounds the magnetic circuit 1 (FIG. 1).
  • the circuit 3 is coiled after assembly;
  • thin layer heads such as those shown in FIG. 2, made by successive deposits of thin layers of magnetic materials of dielectrics and semi-conducting tracks etched so as to make the elements 1, 2 and 3.
  • heads in which the magnetic circuit 1 is not closed at the gap 2 by two symmetrical poles, only ore of the poles playing an active role in the recording. This pole is then the main pole or a single pole head.
  • the main criterion for characterizing a head is the signal-to-noise ratio which should be as high as possible.
  • n number of rotations of the circuit 3
  • ⁇ 'e real part of the effective permeability of the magnetic circuit.
  • the object of the invention is to provide means which can be used to increase the signal-to-noise ratio of a magnetic head.
  • the invention can be applied to different types of heads, and it particularly concerns:
  • thin layer heads for longitudinal and, if necessary, perpendicular recording.
  • main pole or single pole heads for perpendicular recording are main pole or single pole heads for perpendicular recording.
  • the invention therefore concerns a recording/playback magnetic head comprising a magnetic circuit completed by two magnetic poles separated by a gap, the set of magnetic poles and the gap being arranged near a recording surface of a magnetic recording medium, wherein the gap contains at least one layer of superconducting material arranged in a direction substantially perpendicular to the recording surface of the recording medium.
  • the invention also concerns a magnetic recording/playback head in thin layers comprising a magnetic field induction circuit (3) made in thin layers by means of a superconducting material.
  • the invention also concerns a magnetic recording/playback head with a single pole, comprising a single pole provided with a magnetic field induction winding and having a magnetic field emitting end comprising an emitting face placed near a recording surface of a magnetic recording medium so as to emit the magnetic field perpendicularly to the recording surface, comprising at least one sheath made of a superconducting material covering the emitting end except for the emitting face.
  • the invention concerns a method for making a recording/playback head comprising the following steps:
  • FIG. 1 is a massive magnetic head of the prior art
  • FIG. 2 is a thin layer magnetic head of the prior art
  • FIG. 3 is a massive magnetic head according to the invention.
  • FIG. 4 is a thin layer magnetic head according to the invention.
  • FIGS. 5 and 6 show a flat magnetic head according to the invention
  • FIGS. 7 and 8 show a single pole magnetic head
  • FIG. 9 shows a single pole magnetic head according to the invention.
  • FIG. 10 shows an alternative embodiment of the magnetic head of FIG. 9
  • FIG. 11 shows an exemplary embodiment of a part of a magnetic circuit according to the invention.
  • a massive magnetic head of the prior art such as the one shown in FIG. 1, has high recording efficiency because the section of the magnetic circuit can be easily reduced at the gap so as to concentrate the flux.
  • playback it has a signal-to-noise ratio which is not optimized for the following reasons:
  • the quantity R L is preponderant because the inductance L is proportionate, among others, to the section S of the magnetic circuit at the gap 9 owing to the magnetic flux which crosses this gap formed by a material with a permeability which is typically equal to 1.
  • the section S is determined by the width L of the head (which determines the width of the recorded track) and the depth of the gap 1 which is fixed by the machining and wearing conditions of the head:
  • VHS video head will have the following characteristics:
  • the invention enables this problem to be resolved by providing for a superconducting material in the gap 2, as shown in FIG. 3.
  • a superconducting material in the gap 2, as shown in FIG. 3.
  • standard materials have permeability which is very close to 1, thus enabling the field to pass through the gap.
  • the superconducting materials have zero permeability, thus preventing any passage by the field through the gap.
  • the field therefore, cannot be looped except outside the gap, thus enabling an improvement in the signal-to-noise ratio of the massive heads by reducing the inductance (hence the noise of the head).
  • the magnetic circuit is made in two parts and, to obtain a magnetic head magnetic circuit, two parts of magnetic circuits are attached together.
  • FIG. 11 shows, as an example, a part (10) of a magnetic circuit.
  • the inside of at least one part of a magnetic circuit, especially the zone which will serve as an air gap 2 is coated with a layer of a superconducting material 9.
  • the thickness of a layer of this type may be about a few hundreds of angstroms so as to be greater than the depth of penetration of the magnetic field.
  • the thin layer heads have far smaller sections S for two reasons: the manufacturing method enables a reduction in the depth of the gap 1 and, since this type of head functions, in principle, without any contact with the recording medium, it should not undergo any wear and does not require any gap 1 depth.
  • a head for a hard disk will have the following characteristics:
  • the closing of the fields in the gap is ruled out and this, therefore, enables the manufacture of thin layer heads with a gap 1 depth which is greater while, at the same time, preserving high efficiency.
  • This therefore makes the machining of the heads far more simple and enables the use of these heads in contact with the recording medium since the depth 1 then permits a certain degree of wear. Consequently, the production yields and lifetime of the heads is appreciably increased.
  • the resistance R is chiefly due, in this case, to the resistance R B of the winding which may be cancelled if the coil is itself made of a superconducting material.
  • the association, according to the invention, of a gap 2 and a coil 3, both made of superconducting material, thus enables both an increase in the signal and a reduction in noise. It can therefore be especially valuable for a head in which the coil has only one turn.
  • both the coil and the gap can then be made, as shown in FIG. 4, by the same pattern of superconducting material, thus considerably simplifying the making of the head.
  • This type of head made from non-superconducting materials, has a very mediocre signal-to-noise ratio, while a head of this type according to the invention, containing a gap and a coil made of superconducting material, may have a satisfactory signal-to-noise ratio, above all if it is associated with a transformer (fixed or rotating) which is itself superconducting, reducing the signal to a level which is sufficiently greater than the noise of the input amplifier.
  • FIG. 4 represents a thin film magnetic head of this type according to the invention.
  • An insulating substrate 6 is coated with a layer of superconducting material 7. A part of this layer 7 is coated with a layer of a magnetic material (1) up to the edge of the active face 25 of the head. The other part of the layer 7 is coated with insulating material 8'.
  • the flat coil 3 made of a superconducting material and insulated from the preceding layers by an insulating material 8.
  • the insulation of this coil is completed, on top, by an insulating material 8'.
  • the gap 2 On the layer of magnetic material 1, there is made the gap 2 by means of a superconducting material.
  • the magnetic circuit 1 is complemented by a magnetic material which covers the insulating material 8' and the gap 2. The entire unit is itself covered by superconducting material 7'.
  • the method for making a magnetic head of this type will comprise the following steps:
  • the layers 7 and 7' of magnetic material may not be made.
  • FIGS. 5 and 6 show a flat head according to the invention.
  • This head comprises, on a substrate S, two magnetic poles made of thin films 10 and 11, separated by a gap 2.
  • a magnetic circuit 1, carrying magnetic field induction coils 3 and 3', is located on the other side of the poles 10, 11 with respect to the substrate and facing these poles.
  • a flux 10, emitted by the coils, goes through the substrate S and gets closed again by the poles 10 and 11.
  • the gap 2 comprises a superconducting material which, as shown in FIG. 6, makes the entire magnetic flux F created by the coils 3 and 3' go from one pole 10 to the other pole 11 without crossing the gap 2.
  • the longitudinal or perpendicular character of a magnetic recording is determined more by the properties of the recording medium than by the head itself.
  • the type of head shown in FIG. 3 can be used in both cases.
  • heads which are more specifically suited to perpendicular recording namely heads wherein the component of the magnetic field perpendicular to the area of the recording medium is preponderant with respect to the longitudinal component.
  • the basic principle used to this end is to preserve only one pole of the magnetic circuit 1 in the active zone of the head, it being possible for the rest of the circuit to be closed back on to the recording medium by a so-called auxiliary pole or capable of being considered as getting closed again at infinity.
  • a single pole recording head of this type is shown in FIG. 7.
  • the spatial resolution namely the minimum wavelength which can be read by the head, is no longer determined by the thickness e of the gap but by the thickness of the main pole.
  • a resolution of the order of 2e' can be contemplated, but this limit can be reached only for an ideal configuration of the field lines, which cannot be achieved with standard materials because the magnetic field lines, shown in dashes in FIG. 8, leave the pole before the face 16 of the end.
  • This phenomenon arises from the fact that the medium surrounding the pole has a permeabilitY close to 1.
  • means are provided to confine the field within the pole by surrounding it with superconductive material with zero permeability.
  • FIG. 9 shows an exemplary embodiment of a magnetic head of this type.
  • the pole 14 is enveloped, on its different faces apart from the face 16 at the end, by a material of null permeability and, more particularly, by a superconducting material 5.
  • the magnetic field is confined in the magnetic pole 14.
  • the entire field leaves the pole 14 through the end face 16 as shown in dashes in FIG. 9.
  • the efficiency of a head of this type can be improved by working on the shape of the elements 1 and 5 in order to concentrate the flux on the active zone.
  • the magnetic pole 14 has, at its end 15, a contraction used to concentrate the magnetic flux.
  • the superconducting part 9 fits the shape of this contraction.
  • the superconducting material coats the head, namely the magnetic circuit 14 and the coil 3, except for the end face 16.
  • the magnetic circuit 14 can also be closed again by means of an auxiliary pole on the recording medium, provided with a highly permeable sub-layer.
  • the auxiliary pole will be also provided with a sheath, made of a superconducting material channelling the magnetic field.
  • the depth of penetration of the magnetic fields in the material should be sufficiently high
  • critical field of the superconducting material should be sufficiently high.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Magnetic Heads (AREA)
US07/262,719 1987-10-27 1988-10-26 Magnetic recording/playback head comprising a superconducting material Expired - Fee Related US4979064A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8714825 1987-10-27
FR8714825A FR2622341A1 (fr) 1987-10-27 1987-10-27 Tete magnetique d'enregistrement/lecture comportant un materiau supraconducteur

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US4979064A true US4979064A (en) 1990-12-18

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US (1) US4979064A (fr)
EP (1) EP0314557A3 (fr)
JP (1) JPH01140410A (fr)
FR (1) FR2622341A1 (fr)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5097243A (en) * 1987-07-15 1992-03-17 U.S. Philips Corp. Thin-film transformer utilizing superconductive components
US5109312A (en) * 1989-03-20 1992-04-28 Hitachi, Ltd. Magnetic recording apparatus and magnetic head with superconducting material
US5189580A (en) * 1989-06-30 1993-02-23 Ampex Corporation Ultra small track width thin film magnetic transducer
US5198948A (en) * 1990-12-05 1993-03-30 Seagate Technology, Inc. Shielded servo heads with improved passive noise cancellation
US5546255A (en) * 1989-06-15 1996-08-13 Thomson-Csf Integrated recording magnetic head
US6072669A (en) * 1997-03-21 2000-06-06 Indeck; Ronald S. Thin film magnetic write head with preconditioning gap
US20060012503A1 (en) * 2002-11-22 2006-01-19 Jean-Claude Mage Analog/digital converter for microwave frequencies

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5075280A (en) * 1988-11-01 1991-12-24 Ampex Corporation Thin film magnetic head with improved flux concentration for high density recording/playback utilizing superconductors

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US3098181A (en) * 1960-08-29 1963-07-16 Bell Telephone Labor Inc Magnetic circuit using superconductor properties
US3214679A (en) * 1964-04-13 1965-10-26 Richard K Richards Superconductive transformer system
DE1522971A1 (de) * 1967-03-29 1969-10-30 Altenkirch Karl Adolf Gegenstand der Erfindung ist ein Verfahren zur Verbesserung der Dynamik und des Stoerabstandes eines Magnettonkopfes vermittels Schraeganordnung des Spaltes und Verwendung diamagnetischer Stoffe
DE2100090A1 (de) * 1971-01-02 1973-06-07 Assmann Gmbh Wolfgang Magnetkopf fuer aufnahme und/oder wiedergabe
JPS57120221A (en) * 1981-01-14 1982-07-27 Seiko Epson Corp Ring head for vertical magnetization recording and reproduction
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JPS56145514A (en) * 1980-04-14 1981-11-12 Hitachi Ltd Thin-film magnetic head
NL8701664A (nl) * 1987-07-15 1989-02-01 Philips Nv Dunne film magneetkop met inductief overdrachtselement.

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DE588105C (de) * 1932-09-01 1933-11-13 Siemens & Halske Akt Ges Magnet zum Aufzeichnen von Schwingungen auf magnetisierbare Schrifttraeger
US3098181A (en) * 1960-08-29 1963-07-16 Bell Telephone Labor Inc Magnetic circuit using superconductor properties
US3214679A (en) * 1964-04-13 1965-10-26 Richard K Richards Superconductive transformer system
DE1522971A1 (de) * 1967-03-29 1969-10-30 Altenkirch Karl Adolf Gegenstand der Erfindung ist ein Verfahren zur Verbesserung der Dynamik und des Stoerabstandes eines Magnettonkopfes vermittels Schraeganordnung des Spaltes und Verwendung diamagnetischer Stoffe
DE2100090A1 (de) * 1971-01-02 1973-06-07 Assmann Gmbh Wolfgang Magnetkopf fuer aufnahme und/oder wiedergabe
JPS57120221A (en) * 1981-01-14 1982-07-27 Seiko Epson Corp Ring head for vertical magnetization recording and reproduction
JPS57183616A (en) * 1981-05-08 1982-11-12 Canon Inc Magnetic head
JPS60154315A (ja) * 1984-01-20 1985-08-14 Sanyo Electric Co Ltd 磁気ヘツド
EP0199522A2 (fr) * 1985-04-18 1986-10-29 Matsushita Electric Industrial Co., Ltd. Tête magnétique à transformateur-élévateur

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Thin Film and Thin-Film/Ferrite Hybrid Magnetic Heads.

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5097243A (en) * 1987-07-15 1992-03-17 U.S. Philips Corp. Thin-film transformer utilizing superconductive components
US5109312A (en) * 1989-03-20 1992-04-28 Hitachi, Ltd. Magnetic recording apparatus and magnetic head with superconducting material
US5546255A (en) * 1989-06-15 1996-08-13 Thomson-Csf Integrated recording magnetic head
US5189580A (en) * 1989-06-30 1993-02-23 Ampex Corporation Ultra small track width thin film magnetic transducer
US5198948A (en) * 1990-12-05 1993-03-30 Seagate Technology, Inc. Shielded servo heads with improved passive noise cancellation
US6072669A (en) * 1997-03-21 2000-06-06 Indeck; Ronald S. Thin film magnetic write head with preconditioning gap
US20060012503A1 (en) * 2002-11-22 2006-01-19 Jean-Claude Mage Analog/digital converter for microwave frequencies
US7075467B2 (en) 2002-11-22 2006-07-11 Thales Analog/digital converter for microwave frequencies

Also Published As

Publication number Publication date
EP0314557A3 (fr) 1991-09-18
EP0314557A2 (fr) 1989-05-03
JPH01140410A (ja) 1989-06-01
FR2622341A1 (fr) 1989-04-28

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